Most of the tetrahalides of group 14 elements are covalent in nature. However, exceptions exist with the highly electronegative fluorine atom. Both SnF4 and PbF4 are ionic in nature, not covalent. Hence, the statement 'PbF4 is covalent in nature' is incorrect. Additionally, SiCl4 is easily hydrolysed due to the presence of vacant d-orbitals in the silicon atom which can accept electron pairs from water. For germanium, the +4 oxidation state (GeX4) is more stable than the +2 oxidation state (GeX2) because the inert pair effect is not yet dominant (it becomes significant mainly in heavier elements like Sn and Pb).